Question

I habe a main table that i select from and a table with subelements that i select from in a join. Example:

person         skill           person_to_skill
id  | name     id | skill      id | p_id | s_id
------------   ------------    ----------------
1   | jim      1  | sewing     1  | 1    | 2
2   | peter    2  | cooking    2  | 2    | 1
3   | susan    3  | singing    3  | 2    | 3
4   | kevin                    4  | 3    | 1
                               5  | 3    | 2
                               6  | 4    | 3

So now we see, sim has only one skill, peter has two and so forth.
Now if i select from person, koin skill and then also join person_to_skill, but i only want two persons. How do i manage to do so without grouping and thereby not getting all the skills?

Shortly: I want to select two persons from “person” with all their skills.

I tried just using LIMIT but that limits the result rows, not the persons.
If i use GROUP BY i only get one skill per person.
Is this possible without a subselect?

Any ideas anyone?

My Approach so far, changed to work with the example, looks like this:

SELECT p.id,p.name,s.skill
FROM person AS p
LEFT JOIN person_to_skill psk ON (psk.p_id = p.id)
LEFT JOIN skill s ON (s.id = psk.s_id)
ORDER BY p.name
LIMIT 0,2

Answer 1

Limit number of persons at very beginning in subquery then join to them other tables as you’ve already done:

SELECT p.id,p.name,s.skill
FROM (select * from person ORDER BY name LIMIT 0,2) AS p
LEFT JOIN person_to_skill psk ON (psk.p_id = p.id)
LEFT JOIN skill s ON (s.id = psk.s_id)

Added after comment:

If you really can’t use subqueries you can do it using two queries. Firstly select users ids:

select id from person ORDER BY name LIMIT 0,2

and then use those ids in next query:

SELECT p.id,p.name,s.skill
FROM person p
LEFT JOIN person_to_skill psk ON (psk.p_id = p.id)
LEFT JOIN skill s ON (s.id = psk.s_id)
WHERE p.id IN (ids from previous query)